The present invention relates to a communication network comprising a head-end and a plurality of network terminations capable of communicating through a shared communication channel, whereby occasionally contending network terminations try to communicate by simultaneously accessing one or more dedicated slots in upstream communication to the head-end.
The present invention also relates to a protocol for application in the communication network.
Such a communication network is known from WO 99/00931. The known communication network comprises a network hub or head-end and a plurality of network terminations having transmitters/receivers and shared communication channels. Downstream communication from head-end to one or more terminations or upstream communication from one or more terminations to the head-end are made possible by a communication protocol, such as the ALOHA protocol. In particular a flex slotted ALOHA communication protocol is described therein, whereby communication is arranged in consecutive time slots forming a frame. Such a frame comprises data slots containing data cells having information to be transmitted, either downstream, or upstream and dedicated slots containing data cells sent upstream. Such a data cell may for example comprise a reservation request, wherein a termination requests permission from the head-end to transmit upstream data cells in the data slots. If however more than one network termination request permission for communication and they do this within the same dedicated slot or slots then a collision arises therein. In order to resolve this contention between colliding network terminations a retransmission has to be provided for such that the requests do no longer collide. For this situation a protocol generally employs some kind of contention resolution algorithm (CRA) to effect a retransmission of the requests in different dedicated slots. This situation may however lead to a considerable accumulation of processing and communication delays, such that the resolution of the collision may take a considerable amount of time, which reduces the performance of the known communication network.